Known in the optical-fiber component fabrication field is an optical fiber bundle that includes a first set of imaging fibers bundled with a second set of illuminating fibers arranged, for example, circumferentially or, more generally, peripherally, about the imaging fibers as viewed into a plane orthogonal to a longitudinal axis of the imaging and illuminating fibers. Also known to those in the optical fiber industry is that the purpose of such bundles is to form an illuminating “halo” in the vicinity of an object for which an image is to be acquired by, and transported through, the bundled imaging fibers to a remote sensing location. An example of such a “halo” fiber bundle is schematically represented in FIG. 1A. Typically, a device such as that shown in FIG. 1A is assembled from inner and outward fiber bundles, wherein the outward bundle is comprised of illuminating fibers that transport light from a remote source or sources to the light-output end of the outer bundle and the inner bundle is comprised of imaging fibers having an image-input end arranged proximate to focusing optics (e.g., a lens doublet). In order to accommodate and house focusing optics, arrangements such as that of FIG. 1B are fabricated. In the bundle of FIG. 1B, the light-output end of the outer, illuminating bundle extends beyond the image-input end of the inner, imaging bundle in order to define a void or channel for the mounting of the focusing optics. Where, for instance, the inner and outer bundles are cylindrical, a cylindrical void is defined, and analogously for various cross-sectional bundle geometries.
Difficulties abound in the fabrication of illuminable image-transporting fiber bundles of the general configuration shown in FIG. 1B. A first, typical method fabrication involves the separate fabrication of the inner and outer bundles and then the introduction of the inner bundle into the outer bundle. A second method involves the fabrication of the inner bundle and then the assembly and securement of outer-bundle fibers about the inner bundle. In either event, the frequently small and fragile structures require handling by very skilled operators and/or very sophisticated automation equipment, either of which adds to the expense of fabrication. Moreover, the tolerances that are necessary for assembly, particularly those associated with the first method, are difficult to maintain and often reduce the usable surface(s) of the component. Still further, at least the end face of the inner bundle must be finished (e.g., ground and polished) before the outer bundle is arranged about the inner bundle, which increases the exposure of the finished inner face to the potential for damage during subsequent steps in the fabrication process. In still additional, alternative aspects, end portions of mutually fused imaging fibers are machined away to form an image-input face that is recessed with respect to a peripheral light-emission face in order to form a void or channel into which, for example, one or more optical elements (e.g., a lens) is mounted for focusing an image onto the image-input face. In a typical version consistent with the current state of the art, the optics mounted into the void or channel adjacent the image-input face are permanently mounted and, therefore, non changeable. It will be appreciated that machining for the purposes creating a channel to house optics subjects the fused image bundle to damage such as the shattering or splintering of constituent fibers that, as one will readily appreciate, results in the degradation of image input and transport through the image bundle. Moreover, polishing the recessed image-input face is difficult and may result in damage to surrounding illumination fibers.
Accordingly, there exists a need for a simplified assembly including an illuminable image-transporting optical fiber bundle and optics for focusing images into the image-input face thereof. Moreover, there is a need for versions of such an assembly capable of retaining in optical communication with the image-input face, alternative sets of optics.